This study analyzed observational data from field programs in the Persian Gulf and off the coast of California; characterizing the spatial variability of marine atmospheric BL structure in the coastal environment, and the processes that control that structure. Significant results concern the scaling of turbulence under stable conditions - a commonly quoted form for the temperature scale is shown to be formally invalid. The spatial variability of radar propagation conditions over near-coastal waters has been shown to be significant, and the errors in propagation assessment resulting from a failure to account for this variability shown to be unacceptably large. The boundary-layer flow along the coasts of Oregon and northern California during summer are shown to be close to critical over very wide areas, and supercritical over significant regions around every major headland along the coast. The spatial variability of wind stress its curl is found to be large along the coast; the latter is closely tied to sea surface temperature distributions through its modulation of cold upwelling. Stable conditions were widespread and persistent over the cold coastal waters; significant discrepancies between measured and parametrized fluxes were observed within the stable regions.